GB1269519A - Improvements in or relating to machines for grinding, smoothing or polishing optical lenses - Google Patents

Abstract

1,269,519. Grinding lenses. J. & S. WYLDE Ltd. 4 Dec., 1970 [4 Sept., 1969], No. 43890/69. Heading B3D. A device for imparting motion to an optical lens 18 while it is held in contact with the surface of a lens grinding, smoothing or polishing tool 14 comprises a lens holder 42 mounted on a shaft 37 which, at spaced points along its length, passes through or is connected to at least two driven accentric bearing assemblies, one 64 of which is of adjustable eccentricity and the or another of which has two eccentrics 86, 94 driven at two speeds which are in selected ratios to each other so that the assemblies impart to the shaft a substantially uniform but substantially non-repeating motion, i.e. a motion not repeating itself more than once in 500 cycles. The tool is held by a vice 12 operated by an air cylinder 20 in a hollow main body which contains a pump 30 for supplying an abrasive slurry in a sump 34 through a pipe 36 to the upper end 36a of the shaft 37 which is hollow and supplies the slurry to the tool holder 42. The tool consists of a convex or concave surface and may be covered by a layer of woven metal fabric or expanded metal foil. The main body 10 has a pivot 48 about which a workhead 40 containing the shaft 32 is movable to provide access to the tool and workpiece. The shaft is held against rotation about its axis by radial pins 50 slidable in sleeves 52 in a ring 54 having radial arms (56, Fig. 6, not shown) slidable in fixed sleeves 58. Above the pins, the shaft is received in a bearing 70 mounted in an eccentric 64 angularly adjustable to vary its eccentricity in a bush 7 attached to a pulley 74 belt driven from a pulley 78 and mounted by a bearing 80 secured by a mounting 82 to the workhead. Below the pins, the shaft 37 is mounted by a bearing 88 in an eccentric 86 having an arm driven by a stud 92 on a pulley 96 driven by a bolt 98 from a pulley 100. An eccentric 86 is disposed within an outer eccentric 94 secured to a pulley 102 belt driven from a pulley 106 so as to rotate at a speed different from that of eccentric 86, the pulleys 78, 100, 106 being driven from a motor 44. The eccentrics cause the shaft to gyrate or follow a compound motion which is substantially uniform and non-repeating.